Arrangement for deflecting the electron beam of a cathode ray tube in a rosette pattern



March 23, 1965 M. M. BIRNBAUM ETAL 3,175,121

RRANGEMENT FOR DEFLECTING THE ELECTRGN BEAM OF A CATHGDE RAY TUBE IN A ROSETTE PATTERN 3 Sheets-Sheet 1 Filed July 5, 1961 March 23, l965 M. M. BIRNBAUM ETAL 3,175,121

ARRANGEMENT FOR DEFLECTING THE ELECTRON BEAM OF A CATHODE RAY TUBE IN A ROSETTE PATTERN Filed July 3, 1961 5 Sheets-Sheet 2 MAPLIFHERS DIODE MULTIPLIER 13a Jrs March 23, 1965 M. M. BlRNBAuM l-:TAL 3,175,121

ARRANGEMENT FOR DEFLECTING THE ELECTRON BEAM 0F A cATHoDE RAY TUBTJ TN A RosETTE PATTERN Filed July 5, 1961 s sheets-sheet s F i ,3 Size Control 0nly A F i 7 Varying Center nfr| By varying "a,

amplifier gain F 4 symmetrical 8 Centered a' F 5 Varying "n," (the ratio of F 9 Signal Generator Frequencies) NOTE= All Controls May Be Varied Simultaneously i airain Patented Mar. 23, 1965 United States Patent fi Fice ARRANGEMENT FOR DEFLECTING THE ELEC- TRON BEAM F A CATHODE RAY TUBE IN A ROSETTE PATTERN Morris M. Birnbaum, Pasadena, and Phil M. Salomon, Sunland, Calif., assignors to General Precision, Inc., a corporation of Delaware Filed July 3, 1961, Ser. No. 121,479 2 Claims. (Cl. 315-23) The present invention relates to arrangements for deflecting the electron beam of cathode ray tubes in a manner effective to cause the beam to trace predetermined patterns on the phosphor screen of such tubes. In order to defiect the electron beam from a rectilinear course directed against the center of the screen, deliection elements are usually placed at opposite sides of the normal path of the beam, within or externally adjacent to the cathode ray tube.l Such elements may be formed by opposed capacitive plates and/or magnetizing windings, and by applying predetermined voltages to said elements,` electrostatic or magnetic fields are set up between the elements, which detiect the electron beam from its normal course in one or the other direction depending upon the polarity of the voltages at the opposed elements at the moment; and by varying the magnitude and phase relationship of these voltages in an appropriate manner, the composite deiiection effect of the resultant fields may be such as to cause the electron beam to trace predetermined patterns upon the phosphor screen. Well known examples of such arrangements .are the arrangement for producing sine wave patterris on the screen of an oscillograph or the arrangement forcausing the electron beam of a television tube to scan the television screen in a/multitude of successively lower horizontal paths.

It is'an object of our invention to provide a simple and effective arrangement for causing the electron beam of a cathode ray tube to trace a rosette pattern upon the phosphor screen.

'Another object'of the invention is to produce a simple and effective arrangement for sweeping an electron beam across the phosphor screen while tracing rosette patterns in continuous rapid succession.

Still another object of the invention is to provide an arrangement, of the type referred to, which may readily be adjusted to vary the number of the petals of the rosette traced upon the phosphor screen.

Additionally, it is an object of the invention to provide an arrangement, of the type referred to, which may readily be adjusted to vary the size of the petals of the rosette traced upon the screen.

Furthermore, it is an object of the invention to provide an arrangement, of the type referred to, which may be adjusted to produce a rosette having petals of different size. -v

In addition, it is object of the invention to provide an arrangement, ofthe type described, that lmay be set to produce a rosette pattern of a desired non-symmetrical configuration.

Still another object of the invention is to provide an arrangement, of the type referred to, that may be set to provide a rosette pattern wherein the point of origin of the rosette is located at a selected point that is removed from the geometrical center point of the configuration.

Yet another object of the invention is to provide an arrangement, of the type described, that may be set to produce a rolling rosette pattern of any desired shape or size upon the phosphor screen.

These and other objects of the present invention will be apparent from the following description of the accompanying drawings which illustrate a preferred embodiment thereof, and wherein- FIGURE 1 is a block diagram illustrating the principles of the invention;

FIGURE 2 is a circuit diagram illustrating a practical embodiment of the invention;

FIGURES 3, 4 and 5 illustrate the traces of symmetrical rosette patterns of different sizes and different numbers of petals such as may be produced by appropriate adjustment of the arrangement of our invention;

FIGURES 6, 7, 8 and 9 illustrate different non-symmetrcal rosette patterns such as may be produced by appropriate adjustment of the arrangement of our invention.

The present invention proceeds from the polar equation of a rosette which is r=a Sin n0 t l l wherein the factor a determines the diameter of the rosette and n is the number of petals of the rosette. Transformed to the Cartesian system, the corresponding equations read as follows:

x=a sin n0 cos 0 y=a sin 0 sin n0 In accordance with the invention We multiply a sine wave signal of a predetermined frequency with a sine wave signal of a higher frequency and convert the resultant product voltages into a varying deflection field extending across the electron beam of the cathode ray tube in a predetermined direction, and we simultaneously multiply a sine wave signal of said higher frequency with a cosine wave signal of said predetermined frequency and convert the resultant product voltages into a varying deflection eld extending across the electron beam at substantiallv right angles to said first field. Thus Equations 2 and 3 are satisfied, and the varying deflection fields affect the electron beam of the cathode ray tube in such a manner that it traces rosettes upon the phosphor screen of the tube.

In practice, we employ two sine wave generators, one set to generate a sine wave signal of a predetermined frequency and the other one set to generate a sine wave signal of a higher frequency, and we deliver part of the output lof both said generator-s to a first diode bridge multiplier and apply the product voltages of said first multiplier to a first set of a series-connected deflection ele. ments that are arranged along a first axis at opposite sides of the first electron beam of a cathode ray tube and we pass part of the output of said second sine wave generator through a phase shift network to convert it into a cosine signal, and deliver said converted signal and part of the output of said first generator to a second diode bridge multiplier, and apply the product voltages of said second multipler to a second set of series-connected deflection elements that are arranged at opposite sides of the cathode ray tube at either side of the electron beam along an axis substantially at right angles of the axis of said first set of elements. Under the influence of the periodically varying deliection fields set up in this manner, the electron beam of the cathode ray tube traces perfect rosettes upon the phosphor screen of the tube, such as illustrated in FIGURES 3, 4 and 5.

In FIGURE 1 the circle 16 represents a sine wave generator that is setto generate a signal of sin 0 and the circle 12 represents a sine wave generator that is `set to generate a signal of sin n. Sine wave generators are well known in the art and are readily available on the market so that it is unnecessary to describe them here in greater detail. Part of the outputs of both generators are simultaneously applied through impedance matchers represented by the blocks 13a and 13b to an analog multiplier represented by the block 14 where they are continuously multiplied. Suitable high speed analog multipliers are disclosed in pending U.S. patent application No. 4,404 of Morris M.

Birnbaum and William Wichman, which application is assigned to the same assignee as the present application. The product voltages supplied by multiplier 14 are passed through an amplifier represented by the triangle 16 and are applied through a driver represented by the block 18 across two series-connected field producing elements such as magnetizing coils 22a and 22b which may have the form of flat spirals and may be located along an axis y-y directly upon the neck of a cathode ray tube represented by the circle 24. The remaining parts of the outputs of the two generators and 12 are delivered through impedance matchers represented by the blocks 25a and 25b to another analog multiplier represented by the block 26, but the output of the sin 0 generator 10 is first subjected to a phase shift in a suitable phase shift network represented by the block 28, to convert it into a cosine signal; and the product voltages supplied by the multiplier 26 are delivered to an amplier 30 and are applied through a driver 32 across another set of two series-connected held-producing elements such as magnetizing coils 36a and 36b that are located at diametrically opposite points of the neck of cathode ray tube 24 along an axis x-x at right angles to the axis y-y determined by magnetizing coils 22a and 22h.

FIGURE 2 is a diagram illustrating a practical transistorized embodiment of the circuit arrangement represented by the block diagram of FIGURE 1. In FIG- URE 2 the output line of sine wave generator 10 is represented by the movable arm 42 of an adjustable voltage divider network 44 and the output line of generator 12 is represented by the movable arm 38 of an adjustable voltage divider network 40. Part, for instance one-half, of the output of generator 12 is passed through a transistor 50 which is connected to act as phase splitter, and through transistors 52 and 54 which are connected to act as emitter followers and is applied across one set of opposite junctions 56 and S8 of a diode bridge multiplier circuit 14 of the type described in the above-mentioned pending patent application, Serial Number 4,404 of Morris M. Birnbaum and William Wichman. As explained in said application, said bridge is composed of four matched diodes 62 and includes a pair of equal resistors 64 and 65 which are connected across the other set of opposite junctions 66 and 67 thereof and which have their center junction 68 connected to ground. A part, for instance one-half of the signal generated by generator 10 is delivered to the same multiplier bridge 14 through transistors 70 and 72 which act as emitter followers. The low impedance signal derived from said emitter followers is applied to the bridge circuit 14 across a point 74 of a resistor network 76 connected between the bridge junction 56 and 58, and the grounded junction point 68 of resistors 64 and 65. As explained in the repeatedly mentioned patent application of Morris M. Birnbaum and William Wichman, when two signals are applied to the bridge in the described manner, voltages of opposite polarity appear across resistors 64 and 65 and the algebraic sum of these voltages is representative of the products of the applied signals. The voltages appearing across resistor 64 are therefore delivered directly to the base of a transistor 78 that forms part of a voltage adding circuit 80, while the voltages appearing across resistor 65 are iirst applied to the base of a transistor 82 that is connected to act as a voltage inverter. From said voltage inverter they are delivered in inverted condition to the base of another transistor 84 which forms part of the aforementioned voltage adding circuit 80. The voltages appearing in the common collector circuit of transistors 78 and 84 are representative of the sum of the voltages appearing across resistors 64 and 65 of the diode bridge circuit and represent the product of the signals applied to said bridge circuit. Said voltages are delivered to the base of yet another transistor 86 that is connected to act as an amplier and which corresponds to the amplifier 16 of the block diagram shown in FIGURE 1, and the voltages appearing in the collector circuit of said transistor 86 are delivered through a voltage divider 88 to the driver stage represented by the block 18 in FIGURE 1 and from there to the vertically superposed deflection coils 22a and 221) likewise shown in FIGURE 1.

Similarly, a portion of the output of sin n0 generator 12 is applied through transistors 90, 92 and 94 to the opposite junctions 96 and 98 of the second diode bridge multiplier circuit 26, and a portion of the output of sin 0 generator 10 is passed through a phase shift network 100 corresponding to block 28 of FIGURE 1 to convert it into a cosine wave signal, and is delivered through transistors 102 and 104 to the bridge circuit 26 to which it is applied across a point -105 of a resistor network 108 connected between the junctions 96 and 98 of said bridge circuit, and the grounded junction 109 of resistors 110 and 112,; and the voltages of opposite polarity that are developed across the resistors 110 and 112 of said bridge circuit are added in a voltage adding circuit 110 comprising the transistors 112 and 114, after one of said voltages has been inverted in an inverter stage represented by transistor 116. The voltages appearing in the common collector circuit of the transistors 114 and 116 are representative of the products of the sine and cosine signals applied to the multiplier bridge 26. They are passed through a transistor 118 which corresponds to the amplifier 30 of FIGURE 1, and are delivered through voltage divider network v119 and driver 32 to deflection coils 36a and 36]).

Thus, the voltages applied to the vertically superposed deflection coils 22a and 22b are proportional to the product of sin n0 and sin H and the voltages applied to the horizontally aligned deflection coils 36a and 36b are proportional to the product of sin m9 and cos 0. Hence, the system illustrated in FIGURES 1 and 2 satisfies the initially mentioned Equations 2 and 3, and as long as the deflection coils 22a and 22b, 36a and 36h are energized in the described manner, the electron beam emitted by the cathode of tube 24 is continuously deiiected in such a manner as to trace a rosette upon the phosphor screen of the tube, whether it remains otherwise stationary or is swept across the screen.

The size, i.e. the radial length of the rosette petals thus produced upon the phosphor screen of the tube is determined by the amplitude of the wave forms generated by either or both generators 10 and 12. Thus, by varying the amplitude of the waves produced by generator 10 and/or generator 12 in a well known manner, lit is possible to vary the size of the rosettes traced upon the screen of tube 24 in any desired manner, such as vfrom the size shown in FIGURE 3 to the size shown in FIG- URE 4.

The number of petals possessed by the rosettes traced upon the phosphor screen of the cathode ray tube is determined by the ratio it of the frequencies of the waves produced by generators 10 and 12 and is always 2n.l

it is possible to selectively vary the number of the petals of the rosette, for instance, from eight petals as illustrated in FIGURE 3 corresponding to a frequency ratio 4:1 to three petals as illustrated in FIGURE 5 corresponding to a frequency ratio of 1.5 :1. It should here be noted that if the Value of 2n is not an integer, the rosette traced upon the phosphor screen assumes a rolling motion. l

The arrangement of the invention permits also of adjustment to a condition wherein the envelope of the petals of the rosette traced upon the phosphorscreen of the cathode ray tube is non-symmetrical, such as illustrated in FIGURE 6. It is merely necessary to manipulate arms 38 and/'or 42` (FIGURE 2) of the Voltage divider networks 40 and 44, respectively, in the output lines of the generators 10 and 12 in such a way that said voltage dividers deliver predetermined unequal parts of the generator outputs to the diode multipliers 14 and 26, and the rosettes assume non-symmetrical contours in varying degrees. Alternatively, it is possible to cause the arrangement of our invention to deflect the electron beam of the cathode ray tube in such a manner that it traces olf-center rosettes upon the phosphor screen, i.e. rosettes whose point of origin o is located at points removed from the geometrical center point of the created conguration, such as illustrated in FIGURE 7. This may be accomplished by applying one of the signals to the diode bridge 14 or 26, respectively at a point of resistor networks 76 or 108 other than the exact center point thereof. Thus, by varying the location of contact points 74 and 105 on the resistor networks 76 and 108, respectively the location of the point of origin of the rosette may be varied at will.

It will be understood that by varying some or all of the mentioned parameters of the described arrangement simultaneously, a limitless variety of rosettes may selectively be established by the arrangement of our invention. Thus, it is possible to create a rosette of non-symmetric envelope which has only three petals and whose point of origin o lies grossly olf-center such as illustrated in FIG- URE 8, or a rosette of non-symmetrical elliptical envelope which has as many as l2 petals and has its point of origin 0 located closely adjacent to one of the shallow sectors of its periphery, as illustrated in FIGURE 9.

The rosette-producing arrangement of our invention is of extraordinary flexibility. It may be set to produce rosettes of any number of petals, the size of the petals may be varied at will, the point of origin of the rosette may selectively be located anywhere within its envelope, and the shape of its envelope may be varied at will by the simplest of manipulations; and the rosettes may be made to tumble and roll if desired. This is of great signicance in many fields oaf application. For instance, in scanning diapositives of landscapes with a point source of light for the purpose of deriving contour lines therefrom such as described in U.S. patent application, Serial Number 4,404 of Morris M. Birnbaum and William J. Wichman for an Automatic Contour Plotter which is assigned to the same assignee as the present patent application, different types of scanning patterns Ihave proven to produce different degrees of accuracy for different types of diapositives or landscapes of different character.

While we have described our invention with the aid of a particular embodiment thereof, it will be understood that our invention is not limited to the specific circuitry and the specific circuit components shown and described, which may be departed from without departing from the scope and spirit of the invention.

We claim:

1. An adjustable arrangement for deecting the electron beam of a cathode ray tube in predeterminable rosette patterns having points of origin that depart from the geometrical center point of the envelope of the rosette comprising rst and second sine wave generators, a phaseshift network, rst and second means for establishing deiiection lields across the path of the electron beam substantially at right angles to each other, a iirst diode bridge voltage multiplier having rst input means including a resistor connected across one set of opposite diode junctions and second input means including a variable tap on said resistor and connected across said variable tap and a point between the other set of opposite diode junctions, a second diode bridge multiplier having rst and second input means, means for delivering a part of the output of one of said generators to the rst input means of one of said diode bridge multipliers and another part of said output to the first input means of the other diode bridge multiplier, means for delivering a part of the output of the other generator to the second input means of said iirst multiplier and another part thereof through said phaseshift network to the second input means of said second multiplier, means for applying the output of said first multiplier to said first tield detlection means, and means for delivering the output of said second multiplier to said second iield deflection means.

2. An adjustable arrangement for deilecting the electron beam of a cathode ray tube in predeterminable rosette patterns having points of origin that depart from the geometrical center point of the envelope of the rosette comprising iirst and second sine wave generators, a phaseshift network, rst and second means for establishing deflection elds across the path of the electron beam substantially at right angles to each other, first and second diode bridge voltage multipliers each having rst input means including a resistor connected across one set of opposite diode junctions and a second input means including a variable tap on said resistor and connected across said variable tap and a point between the other set of opposite diode junctions, means for delivering a part of the output of one of said rst generators to the first input means of said first diode bridge multiplier and another part of said output to the rst input means of said second diode bridge multiplier, means for delivering a part of the output of the other generator to the second input means of said first diode bridge multiplier and another part thereof through said phase-shift network to the second input means of said second diode bridge multiplier, means for applying the output of said first multiplier to said rst eld deilection means, and means for delivering the output of said second multiplier to said second field deflection means.

References Cited bythe Examiner UNITED STATES PATENTS 2,337,968 12/43 Brown 325-67 2,464,558 3/49 Dammers 315-26 X 2,632,865 3/53 Hales S15-24.1

DAVID G. REDINBAUGH, Primary Examiner.

RALPH G. NILSON, Examiner. 

1. AN ADJUSTABLE ARRANGEMENT FOR DEFLECTING THE ELECTRON BEAM OF A CATHODE RAY TUBE IN PREDETERMINED ROSETTE PATTERNS HAVING POINTS OF ORIGIN THAT DEPART FROM THE GEOMETRICAL CENTER POINT OF THE ENVELOPE OF THE ROSETTE COMPRISING FIRST AND SECOND SINE WAVE GENERATORS, A PHASESHIFT NETWORK, FIRST AND SECOND MEANS FOR ESTABLISHING DEFLECTION FIELDS ACROSS THE PATH OF THE ELECTRON BEAM SUBSTANTIALLY AT RIGHT ANGLES TO EACH OTHER, A FIRST DIODE BRIDGE VOLTAGE MULTIPLIER HAVING FIRST IMPUT MEANS INCLUDING A RESISTOR CONNECTED ACROSS ONE SET OF OPPOSITE DIODE JUNCTIONS AND SECOND INPUT MEANS INCLUDING A VARIABLE TAP ON SAID RESISTOR AND CONNECTED ACROSS SAID VARIABLE TAP AND A POINT BETWEEN THE OTHER SET OF OPPOSITE DIODE JUNCTIONS, A SECOND DIODE BRIDGE MULTIPLIER HAVING FIRST AND SECOND INPUT MEANS, MEANS FOR DELIVERING A PART OF THE OUTPUT OF ONE OF SAID GENERATORS TO THE FIRST INPUT MEANS OF ONE OF SAID DIODE BRIDGE MULTIPLIERS AND ANOTHER PART OF SAID OUTPUT TO THE FIRST INPUT MEANS OF THE OTHER DIODE BRIDGE MULTIPLIER, MEANS FOR DELIVERING A PART OF THE OUTPUT OF THE OTHER GENERATOR TO THE SECOND INPUT MEANS OF SAID FIRST 